Merge pull request #585 from JuliaSymbolics/myb/op

Simplify the construction of `x / 1` and `x / -1`

Author: YingboMa

src/types.jl

@@ -1143,7 +1143,7 @@ end
 
 \(a::Number, b::SN) = b / a
 
-/(a::SN, b::Number) = (b isa Integer ? 1//b : inv(b)) * a
+/(a::SN, b::Number) = (isone(abs(b)) ? b : (b isa Integer ? 1//b : inv(b))) * a
 
 //(a::Union{SN, Number}, b::SN) = a / b
 

test/basics.jl

@@ -301,6 +301,8 @@ end
     @test (2.5x/3x).num == 2.5
     @test (2.5x/3x).den == 3
     @test (x/3x) == 1//3
+    @test isequal(x / 1, x)
+    @test isequal(x / -1, -x)
 end
 
 @testset "LiteralReal" begin